feat: add WeChat search via miku_ai (sogou) (#68)

- wechat channel now supports both search and read
- Search: miku_ai (sogou weixin search) → article list with URLs
- Read: camoufox (stealth Firefox) → full Markdown content
- Doctor shows granular status (search only / read only / both)
- SKILL.md updated with search + read workflow examples

Co-authored-by: Panniantong <panniantong@users.noreply.github.com>

agent_reach/channels/wechat.py

@@ -1,5 +1,9 @@
 # -*- coding: utf-8 -*-
-"""WeChat Official Account articles — check if wechat-article-for-ai is available."""
+"""WeChat Official Account articles — read and search.
+
+Read:   wechat-article-for-ai (Camoufox stealth browser)
+Search: miku_ai (Sogou WeChat search)
+"""
 
 import shutil
 import subprocess
@@ -9,7 +13,7 @@ from .base import Channel
 class WeChatChannel(Channel):
     name = "wechat"
     description = "微信公众号文章"
-    backends = ["wechat-article-for-ai (Camoufox)"]
+    backends = ["wechat-article-for-ai (Camoufox)", "miku_ai (搜狗搜索)"]
     tier = 2
 
     def can_handle(self, url: str) -> bool:
@@ -18,15 +22,36 @@ class WeChatChannel(Channel):
         return "mp.weixin.qq.com" in d or "weixin.qq.com" in d
 
     def check(self, config=None):
+        has_read = False
+        has_search = False
+
         try:
             import camoufox  # noqa: F401
+            has_read = True
         except ImportError:
+            pass
+
+        try:
+            import miku_ai  # noqa: F401
+            has_search = True
+        except ImportError:
+            pass
+
+        if has_read and has_search:
+            return "ok", "完整可用（搜索 + 阅读公众号文章）"
+        elif has_read:
+            return "ok", "可阅读公众号文章（URL → Markdown）。安装 miku_ai 可解锁搜索：pip install miku_ai"
+        elif has_search:
+            return "warn", (
+                "可搜索公众号文章但无法阅读全文。安装阅读工具：\n"
+                "  pip install camoufox[geoip] markdownify beautifulsoup4 httpx mcp"
+            )
+        else:
             return "off", (
-                "需要 wechat-article-for-ai。安装：\n"
+                "需要安装微信公众号工具：\n"
+                "  # 阅读（URL → Markdown）：\n"
                 "  pip install camoufox[geoip] markdownify beautifulsoup4 httpx mcp\n"
-                "  # 或完整安装：\n"
-                "  git clone https://github.com/bzd6661/wechat-article-for-ai.git\n"
-                "  cd wechat-article-for-ai && pip install -r requirements.txt\n"
+                "  # 搜索（关键词 → 文章列表）：\n"
+                "  pip install miku_ai\n"
                 "  详见 https://github.com/bzd6661/wechat-article-for-ai"
             )
-        return "ok", "可读取微信公众号文章（URL → Markdown）"